Field of Invention
The present invention relates to a fan and, in particular, to a fan with a heat-dissipating structure.
Related Art
In a typical fan structure, the impeller is disposed on the motor, and the motor can drive the impeller to rotate. Accordingly, the fan can generate proper airflow to bring the heat of the heating element away. Thus, the manufacturers try to design a fan that can increase the airflow quantity as much as possible. To increase the rotation speed of a fan is a general method for enlarging the airflow quantity, but the rotation speed of a fan has physical limitation in practice. Because the blades of the fan will burden with an extremely high pressure during the high rotation speed, it causes the deformation or break of the blades. The undesired deformation or break of the blades can lead to a very dangerous situation.
Besides, the mechanism and bearing of the motor will bear a higher loading under high rotation speed, so the lifespan of the mechanism is highly threatened. Since the motor is surrounded by the impeller, the heat generated by the motor will be blocked by the impeller and can not be properly dissipated. This situation not only causes the damage of the motor bearing but also increases the temperature inside the system, thereby decreasing the lifespan of the motor as well as the fan.
In addition, some fans capable of generating high air pressure (e.g. a centrifugal fan) are usually applied to the heat-dissipating device of a complex system such as a telecom shelter, a VFD (Variable-frequency Drive) shelter or the likes. However, the heat-dissipating device of the complex system will generate an ambient temperature of 70° C., and the motor operating within the ambient temperature of 70° C. can reach a higher temperature up to 100° C. This high temperature will sufficiently reduce the lifespan of the motor bearing.